The present invention relates to a roller holding apparatus for holding two end shafts of a roller provided to an inking or dampening arrangement of a printing press.
Inking and dampening arrangements are provided to a printing unit of, e.g., an offset printing press to supply an ink and dampening water, respectively, to a surface of a plate mounted on a plate cylinder. The inking arrangement has an ink fountain for storing the ink, an ink fountain roller dipped in the ink in the ink fountain and rotated, and a form roller detachably contacting the plate surface. A large number of vibrating and rubber rollers are disposed between the ink fountain roller and the form roller such that their circumferential surfaces are in contact with each other. The dampening arrangement has a water fountain for storing dampening water, a water fountain roller dipped in the water in the water fountain and rotated, a form dampening roller contacting the plate surface, and a plurality of water ductors disposed between the water fountain roller and the form dampening roller. Then, an image is formed on the surface of the plate with the ink and dampening water supplied to it from these arrangements, and the image is transferred to paper through a blanket cylinder, thus performing printing.
An end portion of a rubber roller provided to, e.g., the inking arrangement, of the inking and dampening arrangements that operate in this manner, has a structure as shown in the partially cutaway front view of FIG. 3 and the side view of FIG. 4. More specifically, a rectangular holding metal member or holder 2 is bolted to the free end portion of a roller arm or lever 1, and an end shaft 3a of a roller holder 3 is inserted in and fixed to a bearing hole 2a of the holding metal member 2 by split clamping. The outer ring of a roll bearing 4 is fitted in a bearing hole 3b of the roller holder 3, and an end shaft 5a of a rubber roller 5 is pressed in the inner ring of the roll bearing 4. The rubber roller 5 contacts a vibrating roller 6 (not shown) and another vibrating roller (not shown). The axis of the rubber roller 5 and that of the roller holder 3 are deviated from each other by t in FIG. 2. Reference numeral 3c denotes a hole in which a wrench is inserted to pivot the roller holder 3.
With this arrangement, during a printing operation, the ink on the rotating vibrating roller 6 is transferred to the rubber roller 5 and distributed, and transferred to another vibrating roller and distributed uniformly in the respective directions. Prior to the printing operation, when the wrench is inserted in the hole 3c to rotate the roller holder 3, the distance between the axes of the roller holder 3 and the vibrating roller 6 is slightly changed by eccentricity, thereby adjusting the nip pressure between the rubber and vibrating rollers 5 and 6.
When the rubber roller 5 is to be replaced due to wear, a bolt 2b fixing the lever 1 and the holder 2 is loosened to be removed, and the rubber roller 5, the roller holder 3, and the holder 2 are integrally taken out of the printing press. The roller holder 3 and the holding metal member 2 removed from the rubber roller 5 are mounted on a new rubber roller 5 outside the printing press and fixed to the lever 1 by the bolt 2b. Then, nip pressure adjustment described above is performed.
In this conventional roller holding apparatus, however, when the rubber roller 5 is to be replaced or maintained, it must be removed from and attached to the lever 1 while the roller holder 3 and the holder 2 are mounted on it. Hence, the operation is cumbersome and time-consuming. Furthermore, the roller holder 3, the holding metal member 2, the bolt 2b, and the like may accidently drop into the printing press to damage another roller or components. Thus, a safe replacement operation is not performed. A holding apparatus of the rubber roller of the inking arrangement has been described so far. However, the same problem arises in other rollers of the inking arrangement or in the rollers of the dampening arrangement.